Organic EL Display Light Diffusion Filling Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Top emission type organic EL display devices face reduced luminance in the oblique direction and attenuated light exiting through a light diffusion color filter, which compromises viewing angle characteristics.
Innovation Solution
Incorporating fine particles with diameters from 300 nm to 30 μm in the filling layer between the substrates to diffuse light resonated by the micro-cavity structure, combined with a color filter and black matrix on the second substrate, enhances light extraction and viewing angle characteristics without significantly increasing manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a light diffusion color filter is provided on the light-extraction side, then viewing angle characteristics are improved, but light is diffused within the color filter causing attenuation and reduction in luminance
Solution Approach 1:
The patent divides the light diffusion function into two separate components: a diffusion layer with fine particles for scattering light, and a color filter layer for wavelength selection. This segmentation allows each layer to perform its specific function efficiently without the negative effects of combining both functions in a single layer, thus improving viewing angle while maintaining luminance.
Solution Approach 2:
The patent introduces a diffusion layer as an intermediary component between the organic EL device and the color filter. This intermediate layer diffuses light before it enters the color filter, reducing the attenuation that would occur if diffusion happened within the color filter itself, thereby preserving luminance while still improving viewing angle characteristics.
2Illumination intensity
If a micro-cavity structure is used to enhance light extraction intensity, then high-luminance light can be extracted on the front side, but the intensity of light is easily reduced in oblique directions
Solution Approach 1:
The patent separates the light enhancement function (micro-cavity structure) from the light diffusion function (diffusion layer with fine particles). The micro-cavity structure maintains high luminance in the front direction, while the subsequent diffusion layer broadens the viewing angle by scattering light in multiple directions, effectively resolving the contradiction between intensity and viewing angle.
Solution Approach 2:
The patent transitions from a one-dimensional light extraction problem (front-side intensity) to a two-dimensional solution by adding a diffusion layer that scatters light in multiple directions. This dimensional change allows the system to maintain high intensity in the original direction while also improving performance in oblique directions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces luminance loss and improves viewing angle characteristics by diffusing light before it exits, maintaining high luminance and directionality while enhancing color purity and emission efficiency.
Implementation Method 1
a structure for resonating the light emitted by the light-emission layer is formed between the reflection electrode and the upper electrode
Implementation Method 2
the filling layer includes fine particles for diffusing the light resonated by the structure and exiting from the upper electrode
Implementation Method 3
a reflection electrode formed below the light-emission layer and reflecting light from the light-emission layer upwards
Data Source
AI summary
An organic EL display device includes a first substrate, a plurality of organic EL devices arranged on the first substrate, a second substrate arranged above the first substrate, and a filling layer arranged between the first substrate and the second substrate, and displays an image on the second-substrate side. The organic EL display device is characterized in that: the organic EL devices each have a light-emission layer, a reflection electrode formed below the light-emission layer and reflecting light from the light-emission layer upwards, and an upper electrode formed above the light-emission layer and having a light transmission property and reflectivity; a structure for resonating the light emitted by the light-emission layer is formed between the reflection electrode and the upper electrode; and the filling layer includes fine particles for diffusing light exiting from the upper electrode added therein.